Assignment 1: Mathy Bits with Percentage Yield

Please complete the questions and submit your file to the correct submission box in Teams.  Use the answer key provided to do a self check of your work and then tally marks earned and submit the file to the same box.

Assignment 2: Lab: Determining the Percentage Yield of a Reaction

Note:  You will not actually be doing this experiment – sample data will be provided for you. 
**Only do the Results, questions and conclusion sections…

Introduction
It is relatively easy to calculate the mass of the product that should be produced from a known mass of a reactant. This is the theoretical yield. However, the mass of the product actually obtained, the experimental yield, is usually less than the theoretical yield. The relationship between these two yields is expressed in a quantity called the percentage yield.

Purpose
Determine the percentage yield of a precipitate.

Material
Chemicals:   lead(II) nitrate,  potassium iodide
Apparatus:  pipette (5 mL), pipette, beaker (250 mL), Erlenmeyer flask (250 mL), funnel, filter paper, electronic balance, wash bottle with distilled water 

Procedure – see this video for how this all works – https://youtu.be/faO9m9JzIgM

1. Dissolve 3.31 g of lead(II) nitrate in 100 mL of distilled water. Label the container as solution A.
2. Dissolve 2 g of potassium iodide in 100 mL of distilled water. Label the container as solution B.
3. Use a pipette to measure 5 mL of the each of the two solutions and add to the beaker. Use a different pipette for each solution to avoid contaminating your stock solutions.
4. Swirl gently.
5. Determine the mass of the filter paper. An accurate measurement is very important.
6. Fold the filter paper in four and place it in the funnel supported by a flask.
7. Slowly pour the mixture into the funnel. Be careful not to overflow the filter paper. Use a wash bottle of distilled water to wash any remaining solid out of the beaker and onto the filter paper.
8. After filtering, let the paper dry overnight.
9. When it is completely dry, determine its mass. Once again, accuracy is important. Be careful not to remove any of the solid product on the filter paper.
10. If time permits, repeat the entire procedure for a second time for accuracy.

Sample Results
Record your observations for each reaction in a table like the one below.

Questions
1. What was your average yield of precipitate?
2. Calculate the percentage yield of your reaction. Use the mass of PbNO₃ to calculate the theoretical yield.
3. Give two reasons why the yield is below 100%.
4. State one way to improve upon the technique and increase the percentage yield.

Conclusion
Briefly and in general terms, state the results for the laboratory. This should be no more than 2 sentences.